lkml.org 
[lkml]   [2018]   [Mar]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid pointers
On (03/14/18 15:09), Petr Mladek wrote:
[..]
> +static const char *check_pointer_access(const void *ptr)
> +{
> + unsigned char byte;
> +
> + if (!ptr)
> + return "(null)";
> +
> + if (probe_kernel_read(&byte, ptr, 1))
^^^^^
Why one byte? sizeof(ptr)?

[..]
> char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> struct printf_spec spec)
> {
> + static const char data_access_fmt[] = "RrhbMmIiEUVNadCDgGO";
> const int default_width = 2 * sizeof(void *);
> + const char *err_msg = NULL;
> +
> + /* Prevent silent crash when this is called under logbuf_lock. */
> + if (*fmt && strchr(data_access_fmt, *fmt) != NULL)
> + err_msg = check_pointer_access(ptr);

Agree with Rasmus, I think switch() is easier.

-ss

\
 
 \ /
  Last update: 2018-03-15 08:59    [W:0.116 / U:0.464 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site